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Dark Sky, Bright Sun
Credit: STS-82 Crew, NASA
Explanation: In low Earth orbit there is not enough atmosphere to diffuse and scatter sunlight, so shadows are black and the sky is dark - even when the Sun shines. The harsh lighting produced this dramatic effect as mission specialist Gregory Harbaugh photographed colleague Joseph Tanner during their second spacewalk to service the Hubble Space Telescope in February 1997. The aft section of the Space Shuttle Discovery is visible in the background with the Sun hanging over a delicate crescent of the Earth's limb. A checklist is attached to Tanner's left arm, and Harbaugh's reflection is just visible in Tanner's visor.

Apollo 17: Boulder on the Moon
Credit: E. Cernan, Apollo 17 Crew, NASA
Explanation: Twenty five years ago humans roamed the Moon. Pictured here during the last moon landing, scientist-astronaut Harrison Schmitt was photographed standing next to a huge, split boulder. Apollo 17 was one of six missions that landed humans on the moon and returned them safely. Apollo 17 explored the unusually dark terrain at the Taurus-Littrow landing site, deployed explosives to test the internal geology of the Moon, and returned the most rocks of any lunar mission.

A Green Flash from the Sun
Credit & Copyright: J. C. Casado
Explanation: Many think it is just a myth. Others think it is true but its cause isn't known. Adventurers pride themselves on having seen it. It's a green flash from the Sun. The truth is the green flash does exist and its cause is well understood. Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green. The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. A green flash is also visible for a rising Sun, but takes better timing to spot. A slight variant of this was caught in the above photograph, where much of the Sun was still visible, but the very top appeared momentarily green. The Sun itself does not turn partly green, the effect is caused by layers of the Earth's atmosphere acting like a prism.

The Center of NGC 6251 is Glowing
Credit: P. Crane & J. Vernet (ESO), FOC, WFPC2 ESA, NASA
Explanation: Something is lighting up the center of galaxy NGC 6251. Leading speculation holds that it is a large black hole not shrouded by gas and dust typically found near the center of a galaxy. Observations taken with the Hubble Space Telescope and released earlier this week indicate a new perspective on the strange beasts that rule the centers of galaxies: a bright central object that is illuminating a surrounding material disk, shown in blue. The lack of reflection from the upper part of the disk indicates that this disk is warped in shape. Although not visible in the above composite image, a huge plasma jet streams out from the central object, perpendicular to the warped disk.

GRB Fireball Persists
Credit: A. Fruchter, E. Pian (STScI), et al., STIS, HST, NASA
Explanation: It's still there. The optical counterpart to the instantly famous gamma-ray burst (GRB) that occurred last February 28th has faded - but not completely. The astronomical community had waited patiently for months for the Earth to proceed far enough along in its orbit so that the Sun's glare no longer ruined inspection of the location of this historic flash. The above picture of GRB 970228, taken September 5th and released just yesterday, shows an extended structure in the center that hasn't changed. However, the arrow indicates a point on the upper right that is now five times dimmer than in preceding months. This fading point fits a model where the GRB originated in a fireball across the universe. The constant brightness of the extended feature indicates that it is not reflected emission from the GRB and might be the host galaxy. Even so, the great GRB mystery is not yet over: for one thing, how come other GRBs don't appear to occur in galactic hosts?

Erupting Sun
Credit: SOHO- EIT Consortium, ESA, NASA
Explanation: On August 27th twisting magnetic fields propelled this huge eruptive prominence a hundred thousand miles above the Sun's surface. The seething plasma of ionized gases is at a temperature of about 150,000 degrees Farenheit and spans over 200,000 miles (about 27 Earths). The Extreme ultraviolet Imaging Telescope (EIT) onboard the space-based SOHO observatory recorded this exquisitely detailed image in the light of ionized Helium atoms from its vantage point in a Halo orbit. This is the largest solar prominence observed by SOHO instruments since they began exploring solar phenomena in early 1996.

Antares and Rho Ophiuchi
Credit and Copyright: D. Malin (AAO), AATB, ROE, UKS Telescope
Explanation: Why is the sky near Antares and Rho Ophiuchi so colorful? The colors result from a mixture of objects and processes. Fine dust illuminated from the front by starlight produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark. Antares, a red supergiant and one of the brighter stars in the night sky, lights up the yellow-red clouds on the upper left. Rho Ophiuchi lies at the center of the blue nebula on the right. The distant globular cluster M4 is visible just below Antares, and to the left of the red cloud engulfing Sigma Scorpii. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum.

The belt of Venus (named after the Roman goddess Venus) is a pink to brownish border separating the dark shadow band of the earth from the sky above it. It is best visible when the atmosphere is cloudless, yet very dusty, just after sunset. The twilight wedge is then rising over the eastern sky and the backscattered red sunlight at the border of the wedge can then be identified as the belt of Venus.

Great pics, and kudos to Hal for initiating and promoting a great thread topic

Thanks Gazill.... I think at some point we should put down the hatred for one another's politics and all get together to enjoy some neat space pictures. HAHA Even NCMike and VTW would find some safe haven in here if they were so inclined. I'm keeping this thread free from the politics and full of wonderment.

One of the biggest galaxy collisions ever observed is taking place at the center of this image. The four white blobs in the middle are large galaxies that have begun to tangle and ultimately merge into a single gargantuan galaxy. The whitish cloud around the colliding galaxies contains billions of stars tossed out during the messy encounter. Other galaxies and stars appear in yellow, orange and red hues. Blue shows hot gas that permeates this distant region of tightly packed galaxies. Credit: NASA/JPL-Caltech/CXO/WIYN/Harvard-Smithsonian CfA

A major cosmic pileup involving four large galaxies could give rise to one of the largest galaxies the universe has ever known, scientists say.

Each of the four galaxies is at least the size of the Milky Way, and each is home to billions of stars.

The galaxies will eventually merge into a single, colossal galaxy up to 10 times as massive as our own Milky Way.

"When this merger is complete, this will be one of the biggest galaxies in the universe," said study team member Kenneth Rines of the Harvard-Smithsonian Center for Astrophysics.

The finding, to be detailed in an upcoming issue of Astrophysical Journal Letters, gives scientists their first real glimpse into a galaxy merger involving multiple big galaxies.

"Most of the galaxy mergers we already knew about are like compact cars crashing together," Rines said. "What we have here is like four sand trucks smashing together, flinging sand everywhere."

Galaxy collisions are a common occurrence in the universe. Our own Milky Way is fated to collide and merge with its neighbor, Andromeda, in about 5 billion years.

Astronomers have observed several clashes involving one big galaxy and several larger ones, and they have also witnessed more major mergers among pairs of big galaxies. But the new findings mark the first time major mergers between multiple hefty galaxies have ever been seen.

NASA's Spitzer Space Telescope serendipitously spotted the quadruple merger during a routine survey of a distant galaxy cluster, called CL0958+4702, located nearly 5 billion light years away. Spitzer's infrared eyes observed an unusually large fan-shaped plume of light emerging from a gathering of four blob-shaped elliptical galaxies. Three of the galaxies are about the size of the Milky Way, while the fourth is three times as large.

The plume turned out to be billions of elderly stars ejected and abandoned during the clash. About half of the stars in the plume will later fall back into the galaxies.

Spitzer observations also show that, unlike most known mergers, the galaxies involved in the quadruple collision are bereft of gas, the source material that fuels star birth. As a result, astronomers predict that relatively few new stars will be born in the new, combined galaxy

On the left of the page look for "Sighting Opportunities" and enter your location. The descriptions are easy to understand so you look in the right direction. The only thing you may need is a basic compass and a watch -- but it's not required.

Viewing is "naked eye" but I've been told a pair of binoculars makes a dramatic difference.

On the left of the page look for "Sighting Opportunities" and enter your location. The descriptions are easy to understand so you look in the right direction. The only thing you may need is a basic compass and a watch -- but it's not required.

Viewing is "naked eye" but I've been told a pair of binoculars makes a dramatic difference.

T Pyxidis: Recurrent Nova
Credit: M. Shara, R. Williams, (STScI), R. Gilmozzi (ESO), NASA
Explanation: What happens when a thermonuclear blast occurs on the surface of a white dwarf star? Over the years astronomers have watched (at a safe distance ...) as, 6,000 light years from Earth in the southern constellation Pyxis, a binary star known as T Pyxidis repeatedly produces these fearsome explosions. This Hubble Space Telescope image of nova T Pyx captures what appear to be blobs rather than the expected shells of material expanding from this interacting star system. Like other binary star systems which produce nova outbursts, T Pyx is composed of a dense white dwarf and a close companion star. An outburst occurs when the temperature and density of the sea of matter dumped from the companion onto the surface of the white dwarf reach the nuclear flash point for hydrogen. While material is violently blown off, the white dwarf itself is not disrupted and soon begins to accumulate more matter from its companion, repeating the cataclysm a few years later.

The Ecliptic Plane
Credit: The Clementine Project
Explanation: The Plane of the Ecliptic is illustrated in this Clementine star tracker camera image which reveals (from right to left) the Moon lit by Earthshine, the Sun's corona rising over the Moon's dark limb, and the planets Saturn, Mars, and Mercury. The ecliptic plane is defined as the imaginary plane containing the Earth's orbit around the Sun. In the course of a year, the Sun's apparent path through the sky lies in this plane. The planetary bodies of our solar system all tend to lie near this plane, since they were formed from the Sun's spinning, flattened, proto-planetary disk. The snapshot above nicely captures a momentary line-up looking out along this fundamental plane of our solar system.